Permanent well completion apparatus



Feb. 4, 1958 usc 2,822,048

PERMANENT WELL COMPLETION APEARATUS 2 Sheets-Sheeh 1 Filed June 4, 1956 V //V VE N TOR.

" GILBERT H-TAUSCH,

vliil A 7' TORNE Y.

PERMANENT WELL COMPLETION APPARATUS Gilbert H. Tausch, Houston, Tex., assignor, by mesne assignments, to Esso Research and Engineering Company, Elizabeth, N. J., a corporation of Delaware Application June 4, 1956, Serial No. 589,333

14 Claims. (Cl. 166-114) This invention is directed to permanent well completion apparatus for producing, working over and servicing a plurality of hydrocarbon productive intervals.

In permanent well completion operations, tubing strings are set permanently during the life of the well and various producing, workover, and servicing operations are performed through these permanently set tubing strings. The workover and servicing operations generally performed on permanently completed wells include squeeze cementing operations wherein existing perforations below the lower end of the tubing are cemented off; perforating or reperforating by means of wire line tools at the same or diilerent producing zones or intervals; sand washing operations; acidizing operations; and other remedial work. A full discussion of permanent well completion operations appears in Permanent Type Well Completion, World Oil, March, 1954.

Briefly, this invention comprises apparatus for working over and servicing a cased borehole penetrating a plurality of spaced apart hydrocarbon productive intervals having parallel tubing strings arranged therein, the lower open ends of which are arranged above the uppermost productive interval. One of the tubing strings is provided with an opening fluidly communicating the interior of said one tubing string and the space between this tubing string and the casing; first packing means is positioned on the tubing strings below the opening adapted to seal off the space between the tubing strings and the casing; second packing means provided with a bore therethrough is positioned in the borehole between the upper: most productive interval and a lower productive interval to seal on the annulus between the bore and the casing and retrievable tubular means is suspendible in said one tubing string and is extensible through the bore of the second packing means.

' This invention also contemplates the use of a novel plugging tool for plugging the lower packer bore when remedial operations are to be performed on an upper productive interval. Briefly, the plugging tool comprises a mandrel having spring biasing means mounted thereon adapted to seat in the packer bore. Sealing means is provided on the mandrel adapted to seal off the annulus between the mandrel and the bore. having a lower closed end is slidably arranged in the mandrel adapted to be connected to one of the tubing strings. The tubular member is provided with first and second spaced apart perforations positioned above and below the second packer means. frangibly secured to the tubular member to close off the second perforations and stop means is frangibly secured to the tubular member below the closure means. slidable sleeve, having first and second positions, is ar- United States Patent A tubular member Closure means is ranged within the tubular member adapted to close off 2,822,048 Patented Feb. 4, 1958 Referring to the drawings:

Fig. 1 is a cross section of a well bore having the apparatus arranged therein for production from upper and lower productive intervals;

Fig. 2 is a cross section of a well bore similar to Fig. 1; however, herein cross over apparatus is provided;

Fig. 3 is a cross section of a well bore having the apparatus arranged therein for working over a lower productive interval;

Fig. 4 is a cross section of a well bore having the apparatus arranged therein for working over an upper productive interval;

Fig. 5 is a sectional view of a plug member employable in the arrangement of the apparatus of Fig. 4.

Referring more particularly to the drawings wherein identical numerals designate identical parts, Figs. 1 through 4 show a borehole 10 penetrating a plurality of productive intervals 11 and 12. A casing 13 extends through productive intervals 11 and 12 and is cemented therein by means of cement 14. A single bore casing packer 15 is positioned in the well bore between upper and lower productive intervals 11 and 12. A recess 16 is provided in the bore 17 of packer 15. A dual bore casing packer 20 is positioned in the well bore above the uppermost productive interval 11. A dual well head assembly 21 is positioned at the surface of the earth 22 and has suspended or connected thereto two parallelly extending tubing strings 23 and 24 which are permanent:- ly set in the well according to permanent well completion practice. Tubing springs 23 and 24 may be the same size but are preferably of different dimensions, as shown, in order that various rates of production may be more efiiciently controlled. These tubing strings are set in the well bore with the dual bore packer 20 positioned adjacent their lower open ends which seals off the space or annulus A between the tubing strings and the casing 13. The packer 20 is provided with a laterally extending passageway 25 which fluidly communicates the lower open end of tubing string 24 and the lower open end of tubing string 23. The latter tubing string is provided with a landing nipple 26 which may be of any desirable type for supporting a tubular extension member such as the landing nipple disclosed in the Composite Catalogue, volume 1, 195253, 19th edition, page 4063.

The dual well head assembly 21 includes a conduit -27 communicating with tubing string 23 and a conduit 28 communicating with tubing string 24. The annulus A between the tubing strings and the casing fluidly communicates with a conduit 29 at the surface of the earth. Suitable valving means is provided in these conduits to control the flow of fluid therethrough. In Fig. 1, a wire line reel 30 is shown connected to a wire line 31 to indicate the means for effecting the lowering and removal of the various apparatuses employed in the workover operations.

Tubing string 23 is provided with an opening 32 above the upper packer 20 which fluidly communicates annulus A and the interior of tubing string 23.

Fig. 1 shows the production apparatus positioned in the well bore. This includes a retrievable tubular extension member 33 having an anchoring means 34 adapted to seat in landing nipple 26. The extension 33 is also provided with packing 35, which may be suitably O-ring, above opening 32 adapted to close ofi or seal the annulus between the tubular extension 33 and tubing string 23. Another packing means 36 which may be suitably chevron packing is provided on tubular extension 33. This packing is positioned below opening 32 and above lateral passageway 25 in packing 20. The annulus between the bore 17 of the lower packer 15 and the tubular extension 33 is sealed off by means of packing 37 provided on tubular extension 33. 'As clearly shown, tubular extension 33 extends downwardlytlirough the lower-packer 15 to a. oint 3 adjacent the lower 'productivezone or interval 12. In producing operations, as shown by the arrows in Fig. 1, production fluids from productive zone 11 pass into casing 13 and thence upwardly throughthe bore 40 of packer 20, into the laterally'extending1 assage'25 and thence into tubing-string' 2'4. These fluidsthen pass upwardly through suitable valving and out c'onduit' 28 at theeaitlissurface. Production fluids 'fro'm'the lower -productive'zone 12 enter the casing'13, pass'upwardly through theinteriono ftubular extension'33 into tubing string 23 and thence through suitable valving into conduit '27 at the earths surface.

Fig. 2 is similar to Fig. 1; however, herein "the flow from the upper and lowerzones hasbeen reversed by providing a cross-over member 50 within a tubular extension '51, which is similar to tubular extension member 33, except upper and'lower perforations 52 and 53 have been provided. Also additional chevron packing 54 is provided on tubular extension 51 to seal off the annulus 40 between the tubular extension 51 and packer 20 below the lateral passage 25 in packer 20. In operation, with the apparatus arranged as in Fig. 2, flow of fluid from upper productive interval 11 enters the cased well bore, passes through port or opening 53 into tubing extension 51 and thence moves upwardly through tubing string 23 and out conduit 27 at the earths surface. Similarly, fluids from lower productive zone 12 flow upwardly through tubular extension 51 out perforation "or opening 52 into passage '25 and thence upwardly through tubing string 24 and into conduit 28 at the earths surface. By use of the'cross-overand tubing strings of different dimensions, it is possible to selectively produce two formations or intervals of different production rates through the tubing string best able to handle the flow.

Fig. 3'shows apparatus for working over the lower zone positioned in the well bore. This apparatus includes a retrievable tubing extension having concentric tubings 60 and 61. A packer 36 is run on the outer tubing to 'providea seal between the opening 32 in tubing 23 and the passage 25 in upper packer 20. The inner and outer concentric tubing strings 60 and 61 of the tubular extension extend through 'the lower packer similarly to 'the previous two embodiments. Suitable anchoring means 34 is employed for seating the tubular extension in landing nipple 26; also packing means 35 is provided to seal off the annulus between tubing string 23 and the outer tubular extension 61. An opening 62 is provided in the outer tubular extension 61 adjacent the opening '32 in tubing string 23. Also an opening 63 is provided in outer tubular extension 61 below the lower packer '15. The annulus between tubings 60 and 61 is closed off at the ends thereof. This arrangement of apparatus is employed for performing workover and servicing operations on the lower zone, for example, circulating fluid, as shown by the arrows may flow down tubing string 23 through tubing 60 and thence adjacent the lower productive interval 12. This type of flow may be employed in cementing or plugging off the lower zone or interval 12. Excess cement from adjacent the lower zone may be circulated out by flow of fluid upwardly through opening 63 in outer tubular extension 61 to opening 62 and thence through opening 32 into annulus A and thence into conduit 29 at the earths surface. The circulating fluid operation, including the cementing technique, may be suitably that such as described in Permanent Type Well Completion World Oil, March 1954 noted supra. The fluid employed may be a slurry of a low fluid loss cement such as that described in the patent to Salathiel, U. S. 2,482,459, or the fluid may be an acid such as a mineral acid or the fluid may be a fracturing fluid such as that described in French Patent 987,352 published August 13,1951or the fluid may be a washing fluid such as water. Other fluids and other low fluid loss cements besides those described may. be used; the type of fluid to be used being dependent upon the type 50f operation desired.

Any leaks'through packing 36 or packing 37 will be readily apparent by flow in tubing string 24. Hence when the fluid is circulating as above described or other remedial operations are being performed on lower interval 12, flow in tubing string 24 will indicate leaks in packings 36 and 37. The circulation 'may be reversed by flowing fluid down annulus A through opening 62 and thence downwardly through the annulus between the concentric tubings and 61 and outwardly through opening 63 adjacent the formation or zone 12 to be treated. The fluid then flows upwardly through tubular extension 60 into tubing string 23 into conduit 27 at the earths surface.

Fig. 4 shows an arrangement of apparatus for working over the upper zone. A tubular extension 65 is provided with anchoring means 34, chevron packing 35, 36 and packing 37 as in the previous embodiments. Herein, however, the tubular extension 65 is preferably pro- 'vided with telescopic joints 66. A plug member -67 is screw threadedly connected to the tubular extension 65 as at 68 and is provided with openings 69 fluidly communicating the productive zone 11 with the interior of tubular extension 65. Although any type plug member may be utilized, the plug member discolsed in Fig. 5 described below is preferred. In the operation for working over the upper zone, fluid such as cement, may be injected into tubing string 23 through conduit 27. The fluid then flows downwardly through tubular extension 65 and out opening 69 to adjacent interval 11. The circulation of fluid is effected by the fluid passing upwardly through the annulus 40 into laterally extending passage 25 and thence upwardly through tubing string 24 to conduit 28. Reverse circulation is effected by flowing fluid downwardly through tubing string 24, passage 25 and opening 69 and upwardly through tubing extension 65 and tubing string 23.

The plug member or tool, noted supra, is shown in Fig. 5. This tool has advantages over present plugging devices since in many instances it may be diflicult to retrieve the plug from the lower packer prior to hardening of cement and the settling or location of debris on the lower plug and the plug itself may be detrimental in later operations. The tool is provided with a mandrel 70 having keys or stop members 71 positioned thereon in slots 72 each of which contains a spring member 73 which latter member normally biases a key or stop member 71 outwardly. The keys 71 are designed to seat in recess 16 of packer l5. Mandrel 70 is also provided with upper and lower spaced chevron packing 74. A tubular member 75 adapted to be screw threadedly connected to tubular extension 65 extends through mandrel 70. The lower end of tubular member 75 is closed as at 76 and the upper end is provided with an enlarged portion 77. This enlarged portion is provided with perforations 78 adapted to be closed by means of a slidable sleeve 79 arranged *on'the inside of tubular member 75. Sleeve 79 is provided with differential areas at the top and bottom, that is, the area at the bottom surface 80 is greater than the area at the top surface 79. Also an indent 81 is provided intermediate its length adapted to connect with a snap ring "82'positio'ned on a shoulder 83 formed on theinterio'r'of tubular member 75. O-ring 84, adjacent the lar er area 80, sealingly engages with the interior of tubular member 75 and O-rings 85 are provided on shoulder 83 to sealingly engage the slidable sleeve O-rings 86 are provided on mandrel 70 to sealingly engage the lower portion of tubular member 75.

The lower end of tubular member 75, below mandrel 70, is provided with perforations 87 which are normally closed by means of a sleeve 88 frangibly connected to tubular member 75 bymeans of frangible pin 89. O-ring's 90 are provided enclosure member 88 to sealingly e'ngage the outer surface of tubular member '75. A stop member '91 is frangibly connected to tubular member 75 below closure-sleeve '88. A fluid passageway 92 in mandrel 70 extends laterally from between packer members 74 to an opening 93 in tubular member 75.

In operation, the plugging tool is connected to the telescopic tubular member 65 and is lowered through the bore 17 of lower packer 15. The keys 71 engage with the detent or recess 16 in the bore 17 under the bias of spring members 73.

Packing 74 seals ofI' the space between the mandrel 70 and the bore of the packer and may be suitably tested by applying fluid pressure within telescopic extension 65 whereby the fluid pressure passes through opening 93 and passage 92. Any leakage of packer 74 or seals 86 will be evidenced by fluid in tubing string 24 or by a pressure drop in tubular extension 65. The assembly may be pressure tested by applying fluid pressure through tubing 24. This tests the eifectiveness of packer 36 adjacent upper packer since any leakage through packer 36 will be evidenced by flow through opening 32 into annulus A. Sleeve 79 remains sealingly closed since the larger area is at the lower end of the sleeve and fluid pressure entering through perforations 78 maintains sleeve 79 closed. A groove 94 may be provided in sleeve 79 adapted to receive snap ring 82 to insure that sleeve 79 remains closed during testing. Fluid pressure within tubular member 75 acting on lower area 80 forces snap ring 82 out of groove 94 as sleeve 79 is urged upwardly when treating operations are begun.

In operation, fluid pressure of a treating fluid such as cement within tubular member 75 acts upon the larger area 80 which moves sleeve 79 upwardly thereby exposing perforations 78. Movement of sleeve 79 upwardly causes snap ring 82 to engage with detent 81 in sleeve 79 thereby retaining sleeve 79' in the upper position. These perforations 78 are similar to the opening 69 in Fig. 4 and the remaining operations are the same as those described in Fig. 4.

When it is desired to remove the tubular extension member from the well bore a suitable wire line tool is lowered by means of reel 30 and wire line 31 to engage with the fishing head of tubular extension member 65. Upward movement causes the closure member 88 to engage with the bottom surface of the mandrel 70. Further force fractures pin 89 thereby exposing perforations 87 and equalizing the pressures within and outside of tubular member 75. This is desirable since the pressure below mandrel 70 may be less than the pressure above the mandrel and within tubular member 75 thereby requiring application of greater force to remove the plugging tool than would otherwise be necessary. Further upward movement causes stop member 91 to engage with closure member 88 which in turn again engages with the lower end of mandrel 70. If suflicient force fails to remove the mandrel 70, that is, if the debris, cement, etc. above mandrel 70 is so great that it can not be removed, stop member 91 fractures thereby permitting removal of.

tubular member 75 from mandrel 70. Mandrel 70 may be removed by means of wireline tools after the debris has been circulated out or otherwise removed. A fishing head is provided on mandrel 70 for this purpose.

Thus the plugging tool permits testing of the lower the tubing extension prior to the hardening of any cement or plastic used in the well.

Having fully described the objects and operation of this device, I claim:

1. Apparatus for working over and servicing a cased' borehole penetrating a plurality of spaced apart hydrocarbon productive intervals comprising parallel eccentric tubing strings arranged in said borehole, the lower open ends of whichare arranged above theuppermost producstrings and said casing, first packing means positioned on said tubing strings below said opening adapted to seal packer and permits retrieving of the lower packer with on the space between said tubing strings and said casing, second packing means provided with a single bore therethrough positioned in said borehole between said uppermost productive intervaland a lower productive interval to seal ofi the annulus between said bore and said casing, and retrievable tubular means suspendible in said one tubing string and extensible through the bore of said second packing means.

2. A retrievable plugging tool adapted to plug a packer bore having a landing nipple thereon comprising a cylindrical mandrel provided with laterally extensible spring biased keys mounted thereon adapted to seat in said packer bore nipple, said mandrel being formed to provide a laterally extending fluid passageway, first spaced apart sealing means on said mandrel adapted to seal oif the annulus between said mandrel and said bore, a tubular member having a lower closed end slidably arranged in said mandrel and adapted to be connected to a tubing string, said tubular member being provided with first, second and third perforations, a closure member enclosing said first perforations frangibly secured to said tubular member, a frangible stop member arranged on said tubular member below said closure member, a slidable sleeve having first and second positions arranged within said tubular member adapted to close oif said second perforations when in said first position and to permit fluid communication through said second perforations when in said second position, said fluid passageway fluidly communicating said third perforations and the space between said first spaced apart sealing means, second spaced apart sealing means arranged on said mandrel adapted to seal off the annulus between said mandrel'and said tubular member above and below said third perforations, and latching means on said tubular member adapted to lock said sleeve in said second position.

3. A retrievable plugging tool adapted to plug a packer bore having a landing nipple thereon comprising a mandrel provided with spring biased means adapted to seat in said packer bore nipple, sealing means provided on said mandrel adapted to seal oil the annulus between said mandrel and said bore, a tubular member having a lower closed end slidably arranged in said mandrel and adapted to be connected to a tubing string, said tubular member being provided with first and second perforations, closure means frangibly secured to said tubular member normally adapted to close off said first perforations, frangible stop means secured to said tubular member below said closure member adapted to prevent movement of said tubular member upwardly through said mandrel, slidable means having first and second positions arranged within said tubular member adapted to close off said second perforations when in said first position and to permit fluid communication through said second perforations when said slidable means is in said second position, and latching means arranged on said tubular-member adapted to lock said slidable means in said second position.

4. A retrievable plugging tool adapted to plug a packer bore having a landing nipple thereon comprising a cylindrical mandrel provided with means mounted thereon adapted to seat in said'packer bore nipple, said mandrel being formed to providea laterally extending fluid passageway, first spaced apart sealing means on said mandrel adapted to seal ofi the annulus between said mandrel and said bore, a tubular member having a lower closed end slidably arranged in said mandrel and adapted to be connected to a tubing string, said tubular member being provided with first, second. and third perforations, a closure member enclosing said first perforations frangibly secured to said tubular member, a frangible stop member arranged on said tubular member below said closure member, a slidable sleeve having first and second positions arranged within said tubular member adapted to close off said second perforations when in said first position and to permit fluid communication through said second perforations when in said second position,

- drel provided withrmeans adapted tosscat in.- said packer ,b ore n pple, sealing llflBfiIlSrQjOXidfiduQH said mandrel a apted to seal off the -annul us ;-.be tweent;said mandrel it ::.-t i end slidably arranged in said tnfllldifilend adapted to be id bore, a tubular m ember; having aa-lowerclosed sosnss o t b n str n asa ubu ammesab nbei pro dsd wi fir and c n per ra ns; closu me trangibly secured; tosaid ;tub 1, lar rnember ormall adapt- .s 1'1 slqs :O s s zp, forat n .t aas b .s cp .means secured tosaid-tubular memberbelow said closure member adapted to prevent; movement ;of- ;sald- 1l;llbular having first and second positions I arrange within said tubular member adapted to: close off; saidseconiperfora- :tions when in saidfirst positio n and to p ermit-jluidicommua sa s thr u a en e f ra ion mh s slidable. means is gin said second; position, 1 and glatching means arranged err-said tubular member; adapte dmtq lock ,said slidable means in. said secondiposition.

: A ar u for Wr t n we rande vicin a. ca

. borehole penetrating a plurality. of;spaced apart hvdrocarbon productive intervals b comprising pasal l,el,= eccentric tubing s trings arranged in said-borehole,,thedower open .ends, of,which ;are arranged ;above,the upperrnost productive interval, one of. said tubing strings being pmvided with an openingv fluidly communicating the. interior 0f. said'one tubing, string, and thespace. between,;said, tubing s trings and said casing, first packing. means, positioned on said tubing stri'ngs, below, said opening adaptedto seal. off the space; betweensaid tubing;strings and said. casing, second packing means provided with a single b r sthfi f through positione d in Said, borehole hetween said fuppermost productive interval and a lower productive interval 11 ssa fi h annu u be ween sai bore n sa d casi g,

an an ...c. pc end ;tu ula .exte io i usp n l sa o tab s t nean extensibl througmhebsre of .sai ,ssssn rackin meansand hav n ffirst sealinsmc m. wis b' lq s sid Qneni11 .dap1ed1o, se l. on the .an- L 1. betwee u sa d on .tubi s tring n: i Y tu extens an [hav n sss n d seal n me ns a r nge here n. adapte .tq saletflth annulusbetweensaid tub lanextension andithe b orepf s aid secondp" 2 e rar u fo Martins ov a disc vi' insacased P931 9 pssst stin -a r ll a it o spac d apar h drocarbon rtqdus iv jin s x l tcsmpri in pa l el. e c tric tubing strings arrangggdiin saidborehole, the'l ovver open d of iskers srrans da v tth utzn rm mo tive interval, one of-sa'id-tubing strings being provided with an opening fluidly communicatingthe interior of said one tubing string ,and thespace between said tubing strings and said casing, ffirstpacking means positioned onsaid tubing strings -below said opening adapted to sealott the space-between saidtubing strings and said casing, second packing means providedwith a bore therethrou'gh positioned in said borehole:betweensaiduppennost productive interval and a lowemproductiveinterval to seal off the annulus between saidboreand :said casing, an open-ended tubular extension suspendibleginsai-d one tubing-string and extensible through the'bore ofsaid second packing means andhavin g .veriically spaced apart.ports p ositioned thereas l st e inamseh p iticn db c a pp s an abo ai rmuermosttpg adapt d t e ed t annulus betweenisaid one tubing string and said tubular nsion ,having a second sealing .means positioned 'fther eon between said spaced apart ports adapted to seal off the annulus-bctweensaid tubular extension and said ;first packing means and having a third sealing means arranged thereon adapted to seal ofi the annulus between said-tubular extension and the bore of said second packing means and crossover means positioned in saidr-tubular extension extendting from above said upper port to below saidlower port-adapted to reverse the flow of fluid from said first; and. second; productive intervals through said tubing strings.

8. Apparatus .for. working over and servicing a cased ,borehole penetrating a tplurality of'spaced apart hydrocarbonproductive intervals comprising .parallel, eccentric tubingstrings-arranged in said borehole,v the lower. open ends-of whicha are arranged above the .uppermost productive interval,. one of saidstubing strings beingprovided withan opening fluidly. communicatingthe-interior of said one tubingstring andthespace between said tubing strings and said easing,tzfirst packing means positioned on said tu'bingstrings, below saidzopening adapted to seal off the space, between. said tubingt strings and saidcasin g, second packin rmeans providedwith a boretherethrough positioned. insaid borehole between said. uppermost productive intervalianda lower productive interval to seal off the annulus .1bCI-WECI] said= bore and said casing, concentric tubular.,extensionsdsuspendible in said-,.one.tubing string and extensible throughthe; bore of said secondv packing means and, havingttfirst sealing means positioned on the outer .tubularextension above said opening adapted to seal ofi. theannulus between, said outer .tubularr extension and said ,One .titbing, string, .secondsea'ling means positioned .on said touter ,tuhular extension Ibelow said opening adapted toseal ofli the annulus betweensaid outer tubular extension,;a,nd ,said one tubing string, and ,third sealing means positioned. on, said outertubular extension adapted to seal on the annulus between the'bore-ofsaid :second packing meansandsaid outer tubular extension, said inner .tubular extension .being open-ended, saidnouten tubular extension being provided with a first port abovesaid second sealing meansifiuidly communicating't-he.annulus between said concent'ric tubings and said one tubing string, and a second port positioned below said third sealing means adapted to Tfluidly communicate the annulu between said concentrictubular extensions and the exterior of said outer tubular extension.

9. Apparatus 'for working over and servicing a cased borehole penetratinga plurality-of spacedapart hydrocarbon productive, intervals comprising-parallel eccentric tubing strings arranged in said borehole, the lower open ends of which arearrange'd above the uppermost 'product-ive interval, one of said tubingstrings being provided with an opening'fluidly communicating the interior of said one tubingstring and the space between said tubing strings and said casing, first packing means positioned on said tubingstrings below said. opening adapted to sealvolf "the space between said tubing strings andsaid casing, second packing means. provided with a bore therethrough positioned in saidflboreholebetween said uppermost productive'iuterval and a'lowerv productive interval toseal elf the annulus between said borean'd said casing, a telescopic tubular extension suspendible in said one tubing string and extensible through the bore of said second packing means and having a'first sealing means positioned .thereonbelow said opening, said tubular extension ineluding a ret'rievable plug member positioned in the'bore of said second packing means and having a port above saidsecondpa'c'king means'and second sealingmeans positioned on said plug member adapted to close otf the annulus between said plug member and the'bore of said secondpacking means.

10. Apparatus as described in claim9 wherein said port above'said second packing means is provided with a fluid pressure operated valve.

11. 'APParatus as described in claim 9 wherein said plug member comprises va mandrellhaving .keys mounted thereon adapted to seat in the bore of said second packing means, a tubular member having a lower closed end slidably arranged in said mandrel, said tubular member being provided with first and second perforations, a closure member enclosing said first perforations frangibly secured to said tubular member, a frangible stop member arranged on said tubular member below said closure member, a slidable sleeve having first and second positions arranged within said tubular member adapted to close 03 said second perforations when in said first position and to permit fluid communication through said second perforations when said sleeve is in said second position and latching means on said tubular member adapted to lock said sleeve in said second position.

12. Apparatus as described in claim 9 wherein said plug member comprises a mandrel having means mounted thereon adapted to seat in the bore of said second packing means, a tubular member having a lower closed end slidably arranged in said mandrel, said tubular member being provided with first and second perforations, a closure member enclosing said first perforations frangibly secured to said tubular member, a frangible stop member arranged on said tubular member below said closure member, a slidable sleeve having first and second positions arranged within said tubular member adapted to close ofi said second perforations when in said first position and to permit fluid communication through said second perforations when said sleeve is in said second position and latching means on said tubular member adapted to lock said sleeve in said second position.

13. A tubular extension for use in working over and servicing a cased and tubed borehole penetrating a plurality of spaced apart hydrocarbon productive intervals comprising inner and outer spaced apart concentric tubing members, said inner concentric tubing member being continuous and open at both ends, anchoring means connected to the upper ends of said concentric tubing members for suspending said concentric tubing members in said tubing, sealing means positioned on said outer concentric tubing member adapted to seal off the annulus between said outer concenn'ic tubing member and said tubing, said outer concentric tubing member being formed to provide first openings adjacent the lower end thereof fluidly communicating the exterior of said concentric tubing members and the annulus therebetween and second openings intermediate the length thereof and vertically spaced from said first openings fluidly communicating the exterior of said concentric tubing members and the annulus therebetween.

14. A tubular extension for use in working over and servicing a cased and tubed borehole penetrating a plurality of spaced apart hydrocarbon productive intervals comprising inner and outer spaced apart concentric tubing members, said inner concentric tubing member being continuous and open at both ends and attached to said outer tubing member, anchoring means connected to the upper ends of said concentric tubing members for suspending said concentric tubing members in said tubing, first sealing means positioned on said outer concentric tubing member adapted to seal olf the annulus between said outer concentric tubing member and said tubing, said outer concentric tubing member being formed to provide first openings adjacent the lower end thereof fluidly communicating the exterior of said concentric tubing members and the annulus therebetween and second openings intermediate the length thereof and vertically spaced from said first openings fluidly communicating the exterior of said concentric tubing members and the annulus therebetween and second sealing means positioned on said outer concentric tubing member between said first and second openings adapted to seal off the annulus between said outer concentric tubing and a well pipe.

References Cited in the file of this patent UNITED STATES PATENTS 1,262,107 Sheasley Apr. 9, 1918 2,760,578 Tausch Aug. 28, 1956 2,772,738 Tausch Dec. 4, 1956 

